// Zlib.cs
// ------------------------------------------------------------------
//
// Copyright (c) 2009-2011 Dino Chiesa and Microsoft Corporation.
// All rights reserved.
//
// This code module is part of DotNetZip, a zipfile class library.
//
// ------------------------------------------------------------------
//
// This code is licensed under the Microsoft Public License.
// See the file License.txt for the license details.
// More info on: http://dotnetzip.codeplex.com
//
// ------------------------------------------------------------------
//
// Last Saved: <2011-August-03 19:52:28>
//
// ------------------------------------------------------------------
//
// This module defines classes for ZLIB compression and
// decompression. This code is derived from the jzlib implementation of
// zlib, but significantly modified.  The object model is not the same,
// and many of the behaviors are new or different.  Nonetheless, in
// keeping with the license for jzlib, the copyright to that code is
// included below.
//
// ------------------------------------------------------------------
//
// The following notice applies to jzlib:
//
// Copyright (c) 2000,2001,2002,2003 ymnk, JCraft,Inc. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in
// the documentation and/or other materials provided with the distribution.
//
// 3. The names of the authors may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL JCRAFT,
// INC. OR ANY CONTRIBUTORS TO THIS SOFTWARE BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
// OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
// EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// -----------------------------------------------------------------------
//
// jzlib is based on zlib-1.1.3.
//
// The following notice applies to zlib:
//
// -----------------------------------------------------------------------
//
// Copyright (C) 1995-2004 Jean-loup Gailly and Mark Adler
//
//   The ZLIB software is provided 'as-is', without any express or implied
//   warranty.  In no event will the authors be held liable for any damages
//   arising from the use of this software.
//
//   Permission is granted to anyone to use this software for any purpose,
//   including commercial applications, and to alter it and redistribute it
//   freely, subject to the following restrictions:
//
//   1. The origin of this software must not be misrepresented; you must not
//      claim that you wrote the original software. If you use this software
//      in a product, an acknowledgment in the product documentation would be
//      appreciated but is not required.
//   2. Altered source versions must be plainly marked as such, and must not be
//      misrepresented as being the original software.
//   3. This notice may not be removed or altered from any source distribution.
//
//   Jean-loup Gailly jloup@gzip.org
//   Mark Adler madler@alumni.caltech.edu
//
// -----------------------------------------------------------------------



using System;
using Interop = System.Runtime.InteropServices;

namespace Ionic.Zlib
{

  /// <summary>
  /// Describes how to flush the current deflate operation.
  /// </summary>
  /// <remarks>
  /// The different FlushType values are useful when using a Deflate in a streaming application.
  /// </remarks>
  public enum FlushType
  {
    /// <summary>No flush at all.</summary>
    None = 0,

    /// <summary>Closes the current block, but doesn't flush it to
    /// the output. Used internally only in hypothetical
    /// scenarios.  This was supposed to be removed by Zlib, but it is
    /// still in use in some edge cases.
    /// </summary>
    Partial,

    /// <summary>
    /// Use this during compression to specify that all pending output should be
    /// flushed to the output buffer and the output should be aligned on a byte
    /// boundary.  You might use this in a streaming communication scenario, so that
    /// the decompressor can get all input data available so far.  When using this
    /// with a ZlibCodec, <c>AvailableBytesIn</c> will be zero after the call if
    /// enough output space has been provided before the call.  Flushing will
    /// degrade compression and so it should be used only when necessary.
    /// </summary>
    Sync,

    /// <summary>
    /// Use this during compression to specify that all output should be flushed, as
    /// with <c>FlushType.Sync</c>, but also, the compression state should be reset
    /// so that decompression can restart from this point if previous compressed
    /// data has been damaged or if random access is desired.  Using
    /// <c>FlushType.Full</c> too often can significantly degrade the compression.
    /// </summary>
    Full,

    /// <summary>Signals the end of the compression/decompression stream.</summary>
    Finish,
  }


  /// <summary>
  /// The compression level to be used when using a DeflateStream or ZlibStream with CompressionMode.Compress.
  /// </summary>
  public enum CompressionLevel
  {
    /// <summary>
    /// None means that the data will be simply stored, with no change at all.
    /// If you are producing ZIPs for use on Mac OSX, be aware that archives produced with CompressionLevel.None
    /// cannot be opened with the default zip reader. Use a different CompressionLevel.
    /// </summary>
    None = 0,
    /// <summary>
    /// Same as None.
    /// </summary>
    Level0 = 0,

    /// <summary>
    /// The fastest but least effective compression.
    /// </summary>
    BestSpeed = 1,

    /// <summary>
    /// A synonym for BestSpeed.
    /// </summary>
    Level1 = 1,

    /// <summary>
    /// A little slower, but better, than level 1.
    /// </summary>
    Level2 = 2,

    /// <summary>
    /// A little slower, but better, than level 2.
    /// </summary>
    Level3 = 3,

    /// <summary>
    /// A little slower, but better, than level 3.
    /// </summary>
    Level4 = 4,

    /// <summary>
    /// A little slower than level 4, but with better compression.
    /// </summary>
    Level5 = 5,

    /// <summary>
    /// The default compression level, with a good balance of speed and compression efficiency.
    /// </summary>
    Default = 6,
    /// <summary>
    /// A synonym for Default.
    /// </summary>
    Level6 = 6,

    /// <summary>
    /// Pretty good compression!
    /// </summary>
    Level7 = 7,

    /// <summary>
    ///  Better compression than Level7!
    /// </summary>
    Level8 = 8,

    /// <summary>
    /// The "best" compression, where best means greatest reduction in size of the input data stream.
    /// This is also the slowest compression.
    /// </summary>
    BestCompression = 9,

    /// <summary>
    /// A synonym for BestCompression.
    /// </summary>
    Level9 = 9,
  }

  /// <summary>
  /// Describes options for how the compression algorithm is executed.  Different strategies
  /// work better on different sorts of data.  The strategy parameter can affect the compression
  /// ratio and the speed of compression but not the correctness of the compresssion.
  /// </summary>
  public enum CompressionStrategy
  {
    /// <summary>
    /// The default strategy is probably the best for normal data.
    /// </summary>
    Default = 0,

    /// <summary>
    /// The <c>Filtered</c> strategy is intended to be used most effectively with data produced by a
    /// filter or predictor.  By this definition, filtered data consists mostly of small
    /// values with a somewhat random distribution.  In this case, the compression algorithm
    /// is tuned to compress them better.  The effect of <c>Filtered</c> is to force more Huffman
    /// coding and less string matching; it is a half-step between <c>Default</c> and <c>HuffmanOnly</c>.
    /// </summary>
    Filtered = 1,

    /// <summary>
    /// Using <c>HuffmanOnly</c> will force the compressor to do Huffman encoding only, with no
    /// string matching.
    /// </summary>
    HuffmanOnly = 2,
  }


  /// <summary>
  /// An enum to specify the direction of transcoding - whether to compress or decompress.
  /// </summary>
  public enum CompressionMode
  {
    /// <summary>
    /// Used to specify that the stream should compress the data.
    /// </summary>
    Compress = 0,
    /// <summary>
    /// Used to specify that the stream should decompress the data.
    /// </summary>
    Decompress = 1,
  }


  /// <summary>
  /// A general purpose exception class for exceptions in the Zlib library.
  /// </summary>
  [Interop.GuidAttribute("ebc25cf6-9120-4283-b972-0e5520d0000E")]
  public class ZlibException : System.Exception
  {
    /// <summary>
    /// The ZlibException class captures exception information generated
    /// by the Zlib library.
    /// </summary>
    public ZlibException()
        : base()
    {
    }

    /// <summary>
    /// This ctor collects a message attached to the exception.
    /// </summary>
    /// <param name="s">the message for the exception.</param>
    public ZlibException(System.String s)
        : base(s)
    {
    }
  }


  internal class SharedUtils
  {
    /// <summary>
    /// Performs an unsigned bitwise right shift with the specified number
    /// </summary>
    /// <param name="number">Number to operate on</param>
    /// <param name="bits">Ammount of bits to shift</param>
    /// <returns>The resulting number from the shift operation</returns>
    public static int URShift(int number, int bits)
    {
      return (int)((uint)number >> bits);
    }

#if NOT
        /// <summary>
        /// Performs an unsigned bitwise right shift with the specified number
        /// </summary>
        /// <param name="number">Number to operate on</param>
        /// <param name="bits">Ammount of bits to shift</param>
        /// <returns>The resulting number from the shift operation</returns>
        public static long URShift(long number, int bits)
        {
            return (long) ((UInt64)number >> bits);
        }
#endif

    /// <summary>
    ///   Reads a number of characters from the current source TextReader and writes
    ///   the data to the target array at the specified index.
    /// </summary>
    ///
    /// <param name="sourceTextReader">The source TextReader to read from</param>
    /// <param name="target">Contains the array of characteres read from the source TextReader.</param>
    /// <param name="start">The starting index of the target array.</param>
    /// <param name="count">The maximum number of characters to read from the source TextReader.</param>
    ///
    /// <returns>
    ///   The number of characters read. The number will be less than or equal to
    ///   count depending on the data available in the source TextReader. Returns -1
    ///   if the end of the stream is reached.
    /// </returns>
    public static System.Int32 ReadInput(System.IO.TextReader sourceTextReader, byte[] target, int start, int count)
    {
      // Returns 0 bytes if not enough space in target
      if (target.Length == 0) return 0;

      char[] charArray = new char[target.Length];
      int bytesRead = sourceTextReader.Read(charArray, start, count);

      // Returns -1 if EOF
      if (bytesRead == 0) return -1;

      for (int index = start; index < start + bytesRead; index++)
        target[index] = (byte)charArray[index];

      return bytesRead;
    }


    internal static byte[] ToByteArray(System.String sourceString)
    {
      return System.Text.UTF8Encoding.UTF8.GetBytes(sourceString);
    }


    internal static char[] ToCharArray(byte[] byteArray)
    {
      return System.Text.UTF8Encoding.UTF8.GetChars(byteArray);
    }
  }

  internal static class InternalConstants
  {
    internal static readonly int MAX_BITS = 15;
    internal static readonly int BL_CODES = 19;
    internal static readonly int D_CODES = 30;
    internal static readonly int LITERALS = 256;
    internal static readonly int LENGTH_CODES = 29;
    internal static readonly int L_CODES = (LITERALS + 1 + LENGTH_CODES);

    // Bit length codes must not exceed MAX_BL_BITS bits
    internal static readonly int MAX_BL_BITS = 7;

    // repeat previous bit length 3-6 times (2 bits of repeat count)
    internal static readonly int REP_3_6 = 16;

    // repeat a zero length 3-10 times  (3 bits of repeat count)
    internal static readonly int REPZ_3_10 = 17;

    // repeat a zero length 11-138 times  (7 bits of repeat count)
    internal static readonly int REPZ_11_138 = 18;

  }

  internal sealed class StaticTree
  {
    internal static readonly short[] lengthAndLiteralsTreeCodes = new short[] {
            12, 8, 140, 8, 76, 8, 204, 8, 44, 8, 172, 8, 108, 8, 236, 8,
            28, 8, 156, 8, 92, 8, 220, 8, 60, 8, 188, 8, 124, 8, 252, 8,
             2, 8, 130, 8, 66, 8, 194, 8, 34, 8, 162, 8, 98, 8, 226, 8,
            18, 8, 146, 8, 82, 8, 210, 8, 50, 8, 178, 8, 114, 8, 242, 8,
            10, 8, 138, 8, 74, 8, 202, 8, 42, 8, 170, 8, 106, 8, 234, 8,
            26, 8, 154, 8, 90, 8, 218, 8, 58, 8, 186, 8, 122, 8, 250, 8,
             6, 8, 134, 8, 70, 8, 198, 8, 38, 8, 166, 8, 102, 8, 230, 8,
            22, 8, 150, 8, 86, 8, 214, 8, 54, 8, 182, 8, 118, 8, 246, 8,
            14, 8, 142, 8, 78, 8, 206, 8, 46, 8, 174, 8, 110, 8, 238, 8,
            30, 8, 158, 8, 94, 8, 222, 8, 62, 8, 190, 8, 126, 8, 254, 8,
             1, 8, 129, 8, 65, 8, 193, 8, 33, 8, 161, 8, 97, 8, 225, 8,
            17, 8, 145, 8, 81, 8, 209, 8, 49, 8, 177, 8, 113, 8, 241, 8,
             9, 8, 137, 8, 73, 8, 201, 8, 41, 8, 169, 8, 105, 8, 233, 8,
            25, 8, 153, 8, 89, 8, 217, 8, 57, 8, 185, 8, 121, 8, 249, 8,
             5, 8, 133, 8, 69, 8, 197, 8, 37, 8, 165, 8, 101, 8, 229, 8,
            21, 8, 149, 8, 85, 8, 213, 8, 53, 8, 181, 8, 117, 8, 245, 8,
            13, 8, 141, 8, 77, 8, 205, 8, 45, 8, 173, 8, 109, 8, 237, 8,
            29, 8, 157, 8, 93, 8, 221, 8, 61, 8, 189, 8, 125, 8, 253, 8,
            19, 9, 275, 9, 147, 9, 403, 9, 83, 9, 339, 9, 211, 9, 467, 9,
            51, 9, 307, 9, 179, 9, 435, 9, 115, 9, 371, 9, 243, 9, 499, 9,
            11, 9, 267, 9, 139, 9, 395, 9, 75, 9, 331, 9, 203, 9, 459, 9,
            43, 9, 299, 9, 171, 9, 427, 9, 107, 9, 363, 9, 235, 9, 491, 9,
            27, 9, 283, 9, 155, 9, 411, 9, 91, 9, 347, 9, 219, 9, 475, 9,
            59, 9, 315, 9, 187, 9, 443, 9, 123, 9, 379, 9, 251, 9, 507, 9,
             7, 9, 263, 9, 135, 9, 391, 9, 71, 9, 327, 9, 199, 9, 455, 9,
            39, 9, 295, 9, 167, 9, 423, 9, 103, 9, 359, 9, 231, 9, 487, 9,
            23, 9, 279, 9, 151, 9, 407, 9, 87, 9, 343, 9, 215, 9, 471, 9,
            55, 9, 311, 9, 183, 9, 439, 9, 119, 9, 375, 9, 247, 9, 503, 9,
            15, 9, 271, 9, 143, 9, 399, 9, 79, 9, 335, 9, 207, 9, 463, 9,
            47, 9, 303, 9, 175, 9, 431, 9, 111, 9, 367, 9, 239, 9, 495, 9,
            31, 9, 287, 9, 159, 9, 415, 9, 95, 9, 351, 9, 223, 9, 479, 9,
            63, 9, 319, 9, 191, 9, 447, 9, 127, 9, 383, 9, 255, 9, 511, 9,
             0, 7, 64, 7, 32, 7, 96, 7, 16, 7, 80, 7, 48, 7, 112, 7,
             8, 7, 72, 7, 40, 7, 104, 7, 24, 7, 88, 7, 56, 7, 120, 7,
             4, 7, 68, 7, 36, 7, 100, 7, 20, 7, 84, 7, 52, 7, 116, 7,
             3, 8, 131, 8, 67, 8, 195, 8, 35, 8, 163, 8, 99, 8, 227, 8
        };

    internal static readonly short[] distTreeCodes = new short[] {
            0, 5, 16, 5, 8, 5, 24, 5, 4, 5, 20, 5, 12, 5, 28, 5,
            2, 5, 18, 5, 10, 5, 26, 5, 6, 5, 22, 5, 14, 5, 30, 5,
            1, 5, 17, 5, 9, 5, 25, 5, 5, 5, 21, 5, 13, 5, 29, 5,
            3, 5, 19, 5, 11, 5, 27, 5, 7, 5, 23, 5 };

    internal static readonly StaticTree Literals;
    internal static readonly StaticTree Distances;
    internal static readonly StaticTree BitLengths;

    internal short[] treeCodes; // static tree or null
    internal int[] extraBits;   // extra bits for each code or null
    internal int extraBase;     // base index for extra_bits
    internal int elems;         // max number of elements in the tree
    internal int maxLength;     // max bit length for the codes

    private StaticTree(short[] treeCodes, int[] extraBits, int extraBase, int elems, int maxLength)
    {
      this.treeCodes = treeCodes;
      this.extraBits = extraBits;
      this.extraBase = extraBase;
      this.elems = elems;
      this.maxLength = maxLength;
    }
    static StaticTree()
    {
      Literals = new StaticTree(lengthAndLiteralsTreeCodes, Tree.ExtraLengthBits, InternalConstants.LITERALS + 1, InternalConstants.L_CODES, InternalConstants.MAX_BITS);
      Distances = new StaticTree(distTreeCodes, Tree.ExtraDistanceBits, 0, InternalConstants.D_CODES, InternalConstants.MAX_BITS);
      BitLengths = new StaticTree(null, Tree.extra_blbits, 0, InternalConstants.BL_CODES, InternalConstants.MAX_BL_BITS);
    }
  }



  /// <summary>
  /// Computes an Adler-32 checksum.
  /// </summary>
  /// <remarks>
  /// The Adler checksum is similar to a CRC checksum, but faster to compute, though less
  /// reliable.  It is used in producing RFC1950 compressed streams.  The Adler checksum
  /// is a required part of the "ZLIB" standard.  Applications will almost never need to
  /// use this class directly.
  /// </remarks>
  ///
  /// <exclude/>
  public sealed class Adler
  {
    // largest prime smaller than 65536
    private static readonly uint BASE = 65521;
    // NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1
    private static readonly int NMAX = 5552;


#pragma warning disable 3001
#pragma warning disable 3002

    /// <summary>
    ///   Calculates the Adler32 checksum.
    /// </summary>
    /// <remarks>
    ///   <para>
    ///     This is used within ZLIB.  You probably don't need to use this directly.
    ///   </para>
    /// </remarks>
    /// <example>
    ///    To compute an Adler32 checksum on a byte array:
    ///  <code>
    ///    var adler = Adler.Adler32(0, null, 0, 0);
    ///    adler = Adler.Adler32(adler, buffer, index, length);
    ///  </code>
    /// </example>
    public static uint Adler32(uint adler, byte[] buf, int index, int len)
    {
      if (buf == null)
        return 1;

      uint s1 = (uint)(adler & 0xffff);
      uint s2 = (uint)((adler >> 16) & 0xffff);

      while (len > 0)
      {
        int k = len < NMAX ? len : NMAX;
        len -= k;
        while (k >= 16)
        {
          //s1 += (buf[index++] & 0xff); s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          s1 += buf[index++]; s2 += s1;
          k -= 16;
        }
        if (k != 0)
        {
          do
          {
            s1 += buf[index++];
            s2 += s1;
          }
          while (--k != 0);
        }
        s1 %= BASE;
        s2 %= BASE;
      }
      return (uint)((s2 << 16) | s1);
    }
#pragma warning restore 3001
#pragma warning restore 3002

  }

}